can someone please explain to me....? explain the reasons for the following procedures in potentiometer experiment: (a)the positive pole of a battery whose emf is required is connected to the same terminal of the potentiometer wire as the positive pole of the driver cell. (b)The protective resister is removed before a final balanced point is determined. (c)A rheostat is sometimes included in the potentiometer circuit with the driver cell but its resistance must not be too high. (d)A standard cell is needed in an experiment to calibrate an ammeter but not in an experiment to measure the internal resistance of a cell. (e)In comparing the resistance of two resistors A and B, the resistors are placed in series in a circuit.